Lens with Facilitated Light Diffusion

ABSTRACT

A lens for distribution of light from a light emitter. The lens has thick and thin wall portions between inner and outer lens surfaces. The thick wall portion(s) are at least twice as thick as the thin wall portion(s). At least one of the inner and outer surfaces has a texturing for diffusion of emitter light passing therethrough. The lens may include at least one interface between two materials with different indices of refraction. At least one surface of the interface may have a texturing for diffusion of emitter light passing therethrough. And, a method for manufacturing of the lens by forming a lens region with a textured surface portion by injecting the thermoplastic elastomer into an injection-molding cavity defined by a shape-forming configuration with a texturing in at least one area of the cavity. The shape-forming configuration is configured to shape a thermoplastic elastomer into such thickness that the set elastomer retains the texturing.

FIELD OF THE INVENTION

This invention relates to lighting devices, and more particularly, toLED lighting and to optics designed for desired LED light distribution.

BACKGROUND OF THE INVENTION

In recent years, the use of light-emitting diodes (LEDs) for variouscommon lighting purposes has increased, and this trend has acceleratedas advances have been made in LEDs and in LED-array bearing devices.Indeed, lighting needs which have primarily been served by fixturesusing high-intensity discharge (HID) lamps, halogen lamps, compactflorescent light (CFL) and other light sources are now increasinglybeginning to be served by LEDs.

Light emitting diodes (LED or LEDs) are solid state devices that convertelectric energy to light, and generally comprise one or more activelayers of semiconductor material sandwiched between oppositely dopedlayers. Light is emitted from the active layer and from all surfaces ofthe LED. A typical high efficiency LED comprises an LED chip mounted toan LED package and encapsulated by a transparent medium. Many differenttypes of LED die can be used individually or in combination in an LEDpackage based on the package application. Possible die include DA, EZ,GaN, MB, RT, TR, UT, and XT LED die, commercially available from Cree,Inc. The efficient extraction of light from LEDs and the quality of thatlight are major concerns in LED package fabrication.

Some efforts have been made to develop small lenses for directing lightemitted by small LED packages, and utilizing lenses intended to redirectsome amount of emitted light to form a desired illumination pattern.However, such lenses have tended to fall short of the most highlydesirable performance and uniformity of distribution of the LED-emittedlight.

LEDs can be fabricated to emit light in various colors. However,conventional LEDs cannot generate white light from their active layers.In order to achieve white color, light from a blue emitting LED has beenmost commonly converted to white light by surrounding the LED with ayellow phosphor. The surrounding phosphor material “downconverts” theenergy of some of the LED's blue light which increases the wavelength ofthe light, changing its color to yellow. While in such arrangements alarge portion of the light is downconverted to yellow, some of the bluelight still passes through the phosphor without being changed such thatthe resulting LED light has a cold-blue white color.

There have been efforts to manufacture white light which resembles thewarm-yellow white color of light produced by the common non-LED lightsources. Certain methods involve the use of LED packages including diesproducing light of different colors which are mixed together to achievethe desirable yellow-white. Such methods require effective mixing ofdifferent color light, as well as efficient distribution of such light.

It would be highly beneficial to provide a lighting apparatus whichproduces a desired illumination with uniform distribution of theintended-color light.

SUMMARY OF THE INVENTION

One aspect of this invention is an improved lens for distribution oflight from a light emitter which has an axis. The lens includes thickand thin wall portions between inner and outer lens surfaces, the thickwall portion(s) being at least twice as thick as the thin wallportion(s). In certain embodiments, an area of at least one of the innerand outer surfaces has texturing for diffusion of emitter light passingtherethrough. The lens is of a molded thermoplastic elastomer.

In certain embodiments, the inner lens surface includes a textured innersurface portion. The inner surface may define an inner cavity receivinglight from the light emitter. In some of such embodiments, the texturedinner surface portion defines an innermost region of the inner cavity.

The textured inner surface portion may be positioned on the emitter axisfor diffusion of axial emitter light. The thin wall region(s) mayinclude(s) the emitter axis and may be between the textured innersurface portion and the outer surface. The innermost region of thecavity may be substantially conical with the vertex on the emitter axis.

In some embodiments, the outer lens surface includes a textured surfaceportion for diffusion of the light received from the inner surface. Thetextured outer surface portion may be positioned on the emitter axis,whereby to further diffuse axial emitter light.

The lens may be substantially rotationally symmetrical about the emitteraxis.

In certain embodiments, the lens includes at least one interface betweentwo materials with different indices of refraction, at least one surfaceof the interface having texturing for diffusion of emitter light passingtherethrough. The texturing may be on a light-receiving surface of theat least one interface. In certain embodiments, the texturing may be onthe light-output surface of the interface.

Another aspect of the present invention is a method for manufacturing ofa lens for distribution of light from a light emitter. In certainembodiments of the inventive method, an injection-molding cavity isprovided. The cavity is defined by a shape-forming configuration whichincludes a surface portion with texturing. A lens region with a texturedsurface portion is molded by injecting a thermoplastic elastomer intothe cavity which is configured to form a wall of such thickness that theset elastomer retains the texturing.

In some embodiments, the lens region with the textured surface portionis a first-formed lens region. The textured surface portion may be of alight-entrance surface of the lens.

The method may include the step of at least partially over-molding alens region formed in the preceding injection-molding shot. Certainversions of the inventive method include the step of over-molding thefirst-formed lens region at surface portion(s) other than the texturedsurface portion.

The lens region with the textured surface portion may be a last-formedlens region. The textured surface portion may be of a light-outputsurface of the lens. The last-formed lens region may be formed by atleast partially over-molding a lens region formed in the precedinginjection-molding shot.

In certain embodiments, each subsequent injection-molding shot is priorto full cooling of the lens region formed in the previous shot. Thisresults in the overmolding being substantially seamless.

The method may further include the step of forming a second texturedsurface portion by over-molding a lens region formed in the precedinginjection-molding shot. The forming step is performed by injecting thethermoplastic elastomer into a cavity defined by a shape-formingconfiguration which includes a surface portion with texturing and isconfigured to form a wall of such thickness that the set elastomerretains the texturing.

The lens region with the second textured surface portion may be alast-formed lens region. The lens region with the second texturedsurface portion may be of a light-output surface of the lens.

The method may further include the step of forming an interface betweentwo materials with different indices of refraction. At least one surfaceof the interface may have texturing for diffusion of emitter lightpassing therethrough. Such step may be by overlaying the texturedsurface portion with a second thermoplastic elastomer.

As used herein, the term “texturing” with reference to a lens surface ora portion thereof means a micro-shape random surface roughness whichcauses diffusion (scattering) of light by random refraction rather thancausing particular directionality. Texturing provides translucency tothe surface. It should be noted that the macro shape even of a texturedsurface may still impose general directionality to the diffused lightpassing through such translucent surface.

As used herein, the degree of texturing is sometimes referred to byreference to the depth of the micro-shape random surface roughness usingMold-Tech® texture standards given in microns of depth. Examples of thetexturing include textures referenced in the Mold-Tech® standards asMT-11000 which is 10μ deep, MT-11010 which is 25μ deep, MT-11030 whichis 50μ deep, MT-11040 which is 75μ deep, MT-11050 which is 110μ deep andMT-11100 which is 150μ deep. Many other textures of various depths maybe used within the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an enlarged perspective cross-sectional view of the inventivelens illustrating texturing on the innermost region of the inner cavity.

FIG. 2 is an enlarged perspective view of light-receiving inner surfacesof the lens of FIG. 1.

FIG. 3 is an enlarged opaque perspective view of light-output outersurfaces of the lens of FIG. 1.

FIG. 4 is an enlarged cross-sectional side view of the lens of FIG. 1.

FIG. 5 is an enlarged cross-sectional side view of a first-formed lensregion including a textured inner-surface portion of the lens of FIG. 1.

FIG. 6 is an enlarged cross-sectional side view of another embodiment ofa lens according to the present invention.

FIG. 7 is an enlarged side view of the lens of FIG. 6 schematicallyshowing light direction through the lens.

FIG. 7A is an enlarged fragment of FIG. 7 showing path of light throughthe lens about the axis.

FIG. 8 is a fragmentary perspective view of yet another embodiment of alens according to the present invention.

FIG. 9 is an opaque perspective view of light-output surfaces of stillanother embodiment of a lens according to the present invention.

FIG. 10 is a perspective view of light-receiving surfaces of the lens ofFIG. 9.

FIG. 11 is a plan view of the light-output surfaces of the lens of FIG.9.

FIG. 12 is a side elevation of the lens of FIG. 9.

FIG. 13 is a plan view of the light-receiving surfaces of the lens ofFIG. 9.

FIG. 14 is a sectional view taken along section 14-14 as indicated inFIG. 13.

FIG. 15 is a sectional view taken along section 15-15 as indicated inFIG. 13.

FIG. 16 is an enlarged exploded perspective view of the lens of FIG. 9schematically showing lens regions formed in each injection-moldingshot.

FIG. 17 is a perspective view of an optical member including a pluralityof lenses according to the present invention.

FIG. 17A is an enlarged fragment of the optical member of FIG. 17showing a cross-section of one of the lenses.

FIGS. 18 and 19 are perspective views of portions of an exemplaryinjection-molding apparatus which has three sets of shape-formingconfigurations in the form of cavities each of which is shaped accordingto a corresponding one of three lens regions.

FIG. 20 is a schematic transparent view of the injection-moldingapparatus illustrating cavities of FIGS. 18 and 19 paired together andshowing nozzles delivering an injection-molding shot to each of thepairs.

FIG. 21 is a partial view of the injection-molding apparatus as in FIGS.18 and 19, but showing three lens regions each formed in thecorresponding cavity by the preceding injection-molding shot(s).

FIG. 22 is an enlarged perspective view of one example of an LED packageand including an array of eight LEDs on a submount and an asymmetricprimary lens overmolded over the LED array.

FIG. 23 is an enlarged perspective view of another example of an LEDpackage and including an array of forty-eight LEDs on a submount and anasymmetric primary lens overmolded over the LED array.

FIG. 24 is an enlarged perspective of yet another example of an LEDpackage which has a single LED on a submount with a hemispheric primarylens overmolded over the LED.

FIG. 25 is an enlarged side view of the LED package of FIG. 29.

FIG. 26 is an enlarged top view of the LED package of FIG. 29.

FIG. 27 is an enlarged top view of another exemplary LED packageincluding an array of four LEDs on a submount and a hemispheric primarylens overmolded over the LED array such that the axis of the primarylens is offset from the axis of the LED array.

FIG. 28 is a transparent perspective view of another example of a lensaccording to the present invention.

FIG. 29 is a plan view of the light-receiving surfaces of the lens ofFIG. 28.

FIG. 30 is a sectional view taken along section 30-30 as indicated inFIG. 29.

FIG. 31 is an enlarged cross-sectional view of a first-formed lensregion including a textured inner-surface portion of the lens of FIG.28.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The Figures illustrate exemplary embodiments of lens 10 for distributionof light from a light emitter 20 which has an axis 21. Lens 10 includesthick wall portions 11 and thin wall portions 12 which are between innerlens surface 30 and outer lens surface 40. It is best seen in FIGS. 4, 6and 14 that thick wall portion(s) 11 may being at least twice as thickas thin wall portion(s) 12.

FIGS. 1-7 illustrate lenses 10 a and 10 b with an area of inner surface30 having texturing 32 for diffusion of emitter light passingtherethrough. FIG. 8 shows an example of lens 10 c with an area of outersurface 40 having texturing 42 for diffusion of emitter light passingtherethrough. Depending on application, there may be lenses with bothinner and outer lens surfaces having textured areas for diffusion ofemitter light passing through such areas.

FIG. 1-5 show that in lenses 10 a and 10 b, inner surface 30 defines aninner cavity 34 receiving light from light emitter 20. It is best seenin FIGS. 1 and 4-7 that textured inner surface portion 33 defines aninnermost region 35 of inner cavity 34. FIGS. 4-7 further show texturedinner surface portions 33 a and 33 b positioned on emitter axis 21 fordiffusion of axial emitter light.

FIGS. 1, 4 and 6 show thin wall region 12 to include emitter axis 21.Thin wall region(s) 12 is/are shown between textured inner surfaceportion 33 and outer surface 40.

In lens 10 a seen in FIGS. 1-5, innermost region 35 a of cavity 34 a isshown substantially conical with the vertex on emitter axis 21.

In lens 10 b seen in FIGS. 6-7, innermost region 35 b of cavity 34 b isshown as having a dome shape, the axis of the dome being on emitter axis21.

FIG. 8 shows lens 10 c with outer lens surface 40 c including a texturedsurface portion 43 for diffusion of the light received from innersurface 30. In FIG. 8, textured outer surface portion 43 is shownpositioned on the emitter axis to diffuse axial emitter light. Inparticular, lens 10 c includes a set of facets on exit geometry tofacilitate color mixing, diffusion and light-beam shaping.

Lenses 10 a, 10 b and 10 c seen in FIGS. 1-8 are substantiallyrotationally symmetrical about emitter axis 21. FIGS. 9-17A illustrateasymmetrical lenses 10 d and 10 e for preferential-side lightdistribution.

For thick-walled optics, a molding process known as “injectioncompression injection” is often used to improve dimensional replication.However, texture is difficult to add to a particular surface as thecompression cycle normally begins after the resin has started to set up.In a one-step injection molding process for forming a thick-walledoptics, cooling and setting of the total thickness of a thermoplasticmaterial takes such length of time during which an attempted texturingis deformed or totally disappears due to sinking of the material. Insome examples of one-step injection molding process for formingthick-walled optics, cooling and setting may takes somewhere between sixand ten minutes. In order to add texture to a thick-walled optic formedin the one-step injection molding, the process requires addition ofcomplex variotherm equipment and sometimes conformal cooling channels.

In contrast, by building the lens in regions (multi-layer molding), theportion of the lens with texture can be molded without sinking andresults in satisfactory reproduction of the texture's structure. In suchmulti-layer molding processes, the texturing may be formed on a lensregion of such thickness of thermoplastic material which cools and setsprior to sinking of the material. Due the rapid cooling and setting, thematerial retains the texturing on its surface. Therefore, a standardprocess known as “pack and hold” can be used which provides easierprocessing and less capital equipment, including a reduced cost of moldsthan those needed in adding texture to a thick-walled optic formed bythe one-step injection molding. The multi-layer molding provides shortercycle times, improved optical control and improved optical efficiency.In some examples of multi-layer molding process for forming thick-walledoptics, cooling and setting of a lens region with surface texturing maytake at little as forty seconds.

FIGS. 1 and 14-17A show lenses 10 a, 10 d and 10 c formed by moldingmultiple regions 15, including regions 151, 152 and 153.

An exemplary multi-layer molding cycle for the first injection-moldingshot forming region 151 a of lens 10 a is 76.5 seconds with 24 secondsof cooling.

FIGS. 1 and 14-16 show regions 151 a and 151 d each as a first-formedlens region which includes respective inner lens surface 30 a and 30 dof lens 10 a and 10 d, respectively. FIG. 1 also shows that, inner andouter surfaces 30 a and 40 a are respectively formed with first-formedlens region 151 a and last-formed lens region 153 a of lens 10 a.

FIG. 15 shows that at least a portion of one of inner and outer surfaces30 d and 40 d of lens 10 d is formed with at least one of regions 151 d,152 d and 153 d molded in a corresponding injection-molding shot.

FIGS. 28-31 illustrate yet another example of a lens 10 f configured forprimarily forward light distribution. It is best seen in FIG. 28-30 thatan inner surface 30 f includes substantially planar front and backsurface portions 301 and 302 and an end surface portion 31 whichincludes front and back segments 311 and 312 each extending inwardlyfrom the respective front and back surface portions 301 and 302. Lens 10f has texturing on front surface portion 301 and front segment 311 ofend surface portion, as seen in FIG. 31. FIG. 31 also shows that innersurfaces 30 f of lens 10 f is formed with region 151 f molded in acorresponding injection-molding shot.

It should be understood that it is within the scope of the presentinvention to have outer light-output lens surfaces formed first andinner light-receiving lens surfaces formed last. The present inventionis not limited to the order of forming lens regions including particularlens surfaces.

FIGS. 18-25 illustrate examples of injection-molding apparatus 50A and50B. Injection-molding apparatuses of this type are described in detailin application Ser. No. 14/508,915, filed on Oct. 7, 2014, whichcontents are incorporated herein by reference in their entirety.

FIGS. 20 and 21 best illustrate three lens regions 151 d, 152 d and 153d each formed by the preceding injection-molding shot(s) in acorresponding cavity 52 of injection-molding apparatus 50A.

Region 151 d is formed in an injection-molding cavity 521 defined by ashape-forming configuration 53 which includes texturing in at least onearea of cavity 521. Shape-forming configuration 53 is configured toshape an injected thermoplastic elastomer into such thickness that theset elastomer retains the texturing (see in FIGS. 14-16).

FIGS. 16 and 21 show lens region 151 d with textured surface portion 33as a first-formed lens region. It is seen in FIGS. 14 and 15 thattextured surface portion 33 d is of inner light-entrance surface 30 oflens 10 d. For lens 10 a, FIG. 1 shows that textured surface portion 33a is of inner light-entrance surface 30 a.

FIGS. 1, 14, 15 and 20 show lens region(s) 151 and/or 152 formed in thepreceding injection-molding shot is/are at least partially over-moldedby subsequently-formed lens regions 152 and/or 153. FIGS. 1, 14 and 15show that first-formed lens region 151 are over-molded at surfaceportion(s) other than the textured surface portion 33.

FIGS. 14 and 15 also show textured surface portion 43 of light-outputsurface 40 as last-formed lens region 153. It is best seen in FIGS. 14and 15 that last-formed lens region 153 d is formed by partiallyover-molding lens region 152 formed in the preceding injection-moldingshot.

Textured surface portion 43 of outer surface 40 is formed during moldingof last-formed lens region 153. Region 153 is molded by injecting thethermoplastic elastomer into cavity 523 which retains the prior-formedlens region(s), as seen in FIG. 20. Cavity 523 is defined by ashape-forming configuration 55 with a second texturing in a second areaof cavity 52. Shape-forming configuration 55 is configured to shape thethermoplastic elastomer into such thickness that the set elastomerretains the second texturing.

FIGS. 18 and 20 show that cavity 522 is defined by a shape-formingconfiguration 54 for molding an intermediate second-formed lens region152.

FIGS. 5 and 31 illustrate examples of regions 151 a and 151 f of lenses10 a and 10 f, respectively. FIG. 5 shows that exemplary region 151 ahas a thickness 17 a of 0.55 mm (0.022 in) measured on axis 21 and athickness 18 a of 2.98 mm (0.117 in) laterally about the texturedsurface portion 33 a. As seen in FIG. 5, thickness 18 a is measured atthe hypotenuse of the right triangle which has one leg that intersectsthe juncture of textured surface portion 33 a and the adjacentnon-textured surface, such intersection being at the point at which thehypotenuse is substantially normal/perpendicular to a surface of thecorresponding shape-forming configuration which forms region 151 a. (Thelegs of such right triangle have lengths of 2.43 mm (0.096 in) parallelto axis 21 and 1.73 mm (0.068 in) orthogonal thereto.)

FIG. 31 shows that exemplary region 151 f has a thickness 17 f of 3.10mm (0.122 in) measured in a direction substantially along axis 21 and athickness 18 f of 2.11 mm (0.0831 in) laterally about the texturedsurface portion 33 a.

The injection-molding apparatus may be configured such that eachsubsequent shot is prior to full cooling of the lens region formed inthe previous shot. Such overmolding of a substantially warm prior-formedlens region achieves smooth substantially seamless blending of theadjacent regions together. Such seamless overmolding is highlybeneficial in formation of LED lenses to facilitate accuratetransmission of light therethrough.

Lens regions which have the texturing are of a molded thermoplasticelastomer such as suitable polymeric materials. While the entire lenscan be of the same material, some versions of the lens may includeregions of different polymeric materials. In some embodiments, lensregions which include outer lens surfaces may be of an acrylic. A widevariety of optical-grade acrylics can be used, and are available fromvarious sources, including: Mitsubishi Rayon America, Inc.; ArkemaGroup; and Evonik Cyro LLC. Some optical-grade acrylics useful in thisinvention have an index of refraction 1.49

In certain embodiments, other lens regions may be of a second polymericlayer such as a liquid silicone resin (LSR). A wide variety ofoptical-grade LSRs can be used, and are available from various sources,such as: The Dow Chemical Company; Wacker Chemie AG; and MomentivePerformance Materials Products. Some optical-grade LSR materials have anindex of refraction of 1.41.

FIGS. 17 and 17A show lens 10 e which includes an interface 60 betweenfirst thermoplastic elastomer 61 and second thermoplastic elastomer 62with different indices of refraction. In lens 10 e shown in FIG. 17A,interface 60 has surface 63 having texturing 64 for diffusion of emitterlight passing therethrough. FIG. 17A shows that surface 63 withtexturing 64 is light-receiving surface.

Interface 60 between first and second polymers 61 and 62 may be formedby first molding a lens region 16 which includes surface 63 havingtexturing 64. Lens region 16 may be molded by injecting thermoplasticelastomer 61 into cavity defined by a shape-forming configuration withat least one area of the cavity configured for causing texturing. Suchshape-forming configuration is configured to shape a thermoplasticelastomer into such thickness (see in FIG. 17A) with which the setelastomer retains the texturing. Interface 60 is then formed byoverlaying textured surface 63 with second thermoplastic elastomer 62.

FIGS. 22-27 show light emitter 20 in the form of an LED package 23 whichhas a primary lens 24 over the at least one LED 22. In such embodiments,the inventive lens is a secondary lens placed over primary lens 24.Light emitter 20 may be of the type illustrated in FIGS. 24-26 whichshow LED package 23D with single LED 22 on a submount 26 and hemisphericprimary lens 24D coaxially overmolded on submount 26 over LED 22.

FIGS. 22 and 23 illustrate exemplary LED packages 23A and 23B eachincluding an array of LEDs 22 on an LED-populated area 25 which has anaspect ratio greater than 1, and primary lens 24 being overmolded on asubmount 26 over LED-populated area 25. It is seen in FIG. 23 that thearray may include LEDs 22 emitting different-wavelength light ofdifferent colors such as including red LEDs along with light green orother colors to achieve natural white light. Light emitters of the typeas LED packages 23A and 23B are described in detail in application Ser.No. 13/441,558, filed on Apr. 6, 2012, and in application Ser. No.13/441,620, filed on Apr. 6, 2012. The contents of both applications areincorporated herein by reference in their entirety.

FIGS. 22, 22 and 27 illustrate versions of LED light emitter 20configured to refract LED-emitted light in a forward direction (i.e.,toward preferential side P). In each LED package 23A, 23B and 23C, eachLED array defines an emitter axis. FIGS. 22 and 23 illustrate primarylens 24A configured to refract LED-emitted light forward. FIG. 27 showshemispheric primary lens 24C having a centerline 240 offset from theemitter axis. It should be understood that for higher efficiency, LEDemitter 20 may have a primary lens having both its centerline offsetfrom the emitter axis and also being shaped for refraction ofLED-emitted light toward preferential side P. In FIGS. 22 and 23,primary lens 24A is shown as asymmetric.

While the principles of the invention have been shown and described inconnection with specific embodiments, it is to be understood that suchembodiments are by way of example and are not limiting.

1. A lens for distribution of light from a light emitter, the lenscomprising thick and thin wall portions between inner and outer lenssurfaces, the thick wall portion(s) being at least twice as thick as thethin wall portion(s), at least one of the inner and outer surfaceshaving a texturing for diffusion of emitter light passing therethrough.2. The lens of claim 1 wherein a lens region having the texturing is ofa molded thermoplastic elastomer.
 3. The lens of claim 1 wherein theinner lens surface includes a textured inner surface portion.
 4. Thelens of claim 3 wherein the inner surface defines an inner cavityreceiving light from the light emitter, the textured inner surfaceportion defining an innermost region of the inner cavity.
 5. The lens ofclaim 4 wherein: the light emitter has an axis; and the textured innersurface portion is positioned on the emitter axis for diffusion of axialemitter light.
 6. The lens of claim 5 being substantially rotationallysymmetrical about the emitter axis.
 7. The lens of claim 6 wherein thethin wall region(s) include(s) the emitter axis and is/are between thetextured inner surface portion and the outer surface.
 8. The lens ofclaim 6 wherein the innermost region of the cavity is substantiallyconical with the vertex on the emitter axis.
 9. The lens of claim 3wherein the outer lens surface includes a textured surface portion fordiffusion of the light received from the inner surface.
 10. The lens ofclaim 1 wherein the outer lens surface includes a textured surfaceportion for diffusion of light received from the inner surface.
 11. Thelens of claim 10 wherein: the light emitter having an axis; and thetextured outer surface portion is positioned on the emitter axis,whereby to further diffuse axial emitter light.
 12. The lens of claim 11being substantially rotationally symmetrical about the emitter axis. 13.A method for manufacturing of a lens for distribution of light from alight emitter, the method comprising the steps of: providing aninjection-molding cavity defined by a shape-forming configuration with atexturing in at least one area of the cavity, the shape-formingconfiguration being configured to shape a thermoplastic elastomer intosuch thickness that the set elastomer retains the texturing; and forminga lens region with a textured surface portion by injecting thethermoplastic elastomer into the cavity.
 14. The method of claim 13wherein the lens region with the textured surface portion is afirst-formed lens region.
 15. The method of claim 14 further includingthe step of over-molding the first-formed lens region at surfaceportion(s) other than the textured surface portion.
 16. The method ofclaim 14 wherein the textured surface portion is of a light-entrancesurface of the lens.
 17. The method of claim 14 further including thestep of at least partially over-molding a lens region formed in thepreceding injection-molding shot.
 18. The method of claim 17 whereineach subsequent injection-molding shot is prior to full cooling of thelens region formed in the previous shot.
 19. The method of claim 14further including the step of forming a second textured surface portionby over-molding a lens region formed in the preceding injection-moldingshot, the forming step being by injecting the thermoplastic elastomerinto the cavity which retains the prior-formed lens region(s) and isdefined by a shape-forming configuration with a second texturing in asecond area of the cavity, the shape-forming configuration beingconfigured to shape the thermoplastic elastomer into such thickness thatthe set elastomer retains the second texturing.
 20. The method of claim19 wherein the lens region with the second textured surface portion is alast-formed lens region.
 21. The method of claim 20 wherein the lensregion with the second textured surface portion is of a light-outputsurface of the lens.
 22. The method of claim 13 wherein the lens regionwith the second textured surface portion is a last-formed lens region.23. The method of claim 22 wherein the last-formed lens region is formedby at least partially over-molding a lens region formed in the precedinginjection-molding shot.
 24. The method of claim 23 wherein eachsubsequent injection-molding shot is prior to full cooling of the lensregion formed in the previous shot.
 25. The method of claim 23 whereinthe textured surface portion is of a light-output surface of the lens.26. The method of claim 13 further including the step of forming aninterface between two materials with different indices of refraction byoverlaying the textured surface portion with a second thermoplasticelastomer.
 27. A lens for distribution of light from a light emitter,the lens comprising: thick and thin wall portions between alight-receiving inner surface and a light-output outer surface, thethick wall portion(s) being at least twice as thick as the thin wallportion(s); and at least one interface between two materials withdifferent indices of refraction, at least one surface of the interfacehaving texturing for diffusion of emitter light passing therethrough.28. The lens of claim 27 wherein the texturing is on a light-receivingsurface of the at least one interface.
 29. The lens of claim 27 whereinthe light-receiving inner surface includes a textured inner surfaceportion defining an innermost region of an inner cavity receiving lightfrom the light emitter.
 30. The lens of claim 27 wherein thelight-output outer surface includes a textured outer surface portion fordiffusion of received light.